BSF S70: Part 3
by B.B. Pelletier
Announcement: Here’s this week’s winner of Pyramyd Air’s Big Shot of the Week on their facebook page. He’ll receive a $50 gift card.
The BSF S70 is a classic breakbarrel air rifle from the first days of magnum airguns.
Today is accuracy day for the BSF S70 and shooting it makes me feel like a kid again. Or at least like a younger man. Everything about this rifle puts me in mind of the timeframe when it was popular. It was contemporary with the Diana model 27 and the FWB 124, so when I hold it, it’s the 1970s once again.
Although the S70 has a scope rail and I could use a BKL scope mount to attach a small scope, I opted to conduct this accuracy test with the sights that were on the gun when I got it. In this case, the front sight is a tall, hooded post and bead that came from the factory, but the rear sight was removed. In its place is a beautiful Williams peep sight with target adjustment knobs that looks like a million dollars. We shall see how well it performs.
The front sight that came on the rifle is already tall. It would ruin the look of this vintage air rifle to extend it any higher.
My decision to use open sights was to see whether if eyes had recovered from the problems I had a month ago. No glasses were used this time. I did light the target with a 500-watt lamp, though, and that’s a huge help is defining the front sight against the bull.
Not wanting to put a couple rounds through the walls of my house, I opted to shoot at 10 meters instead of 25 yards. But the target I selected was also a 10-meter bullseye target, so the scale of target size to the distance shot was kept standard.
It’s difficult to sight a bullseye target with a bead front sight and a rear aperture, but I used a six o’clock hold nevertheless. The bull rested on top of the bead, which was centered in the rear aperture. It sounds flaky but it’s actually possible to be very precise if you get your eye close enough to the rear aperture.
RWS Hobby pellets were used for sight-in, and they produced an agreeably small group, although it was quite a bit higher than the aim point. No problem, I thought. I would just adjust the peep lower.
What’s this? It’s already adjusted as low as it will go? That’s when I discovered why this rifle has been handed off from owner to owner over the years. The beautiful Williams peep sight doesn’t adjust low enough to get the rifle on target at 10 meters. It shoots about 3.75 inches to 4.50 inches high at that range, even when you are holding at six o’clock. To shoot any lower, you would need to install a higher front sight, but the one on the gun is already quite high. The only reasonable solution would be to scope the rifle, but that would detract from the rifle’s vintage character. However, it’s either that or shoot at 50 yards and more all the time.
That was a setback, but I didn’t let it stop me from testing the gun. I don’t care where the group falls, as long as all the pellets are going to the same place.
Remember back when motorcycles all had chains and you had to oil the links often to keep them running smooth? Well, airguns of this vintage are similar, in that they loosen their stock screws as you shoot, so you have to keep screwdrivers on hand and keep checking the screw tension. I found the stock screws loose after the first 15 shots, and I tightened them. They remained tight for the rest of the test, but they’ll loosen again.
You may recall that I had oiled the piston seal of this rifle during the velocity test and proved that the gun is a full U.S.-powered air rifle. In a gun of this vintage, that also means vibration. Each shot was slightly buzzy, and I could discern differences in the vibration with certain pellets.
I oiled the piston seal, again, after completing the velocity test and allowed the rifle to sit on its butt for a week while the oil soaked into the leather piston seal. The result was a couple of expected detonations when I first fired the gun during this test, but then it settled down to deliver consistent velocity shot after shot.
The trigger is already showing signs of becoming smoother with use. By the end of accuracy testing, I’d become familiar with the let-off and was better able to control my trigger squeeze.
The first pellet I tried was the 7.9-grain Crosman Premier. It shot high, though not as high as the RWS Hobby was shooting during sight-in. The firing cycle vibration with this pellet was also noticeably reduced from that of the Hobby pellet. My 10-shot group was agreeably tight, with a single pellet straying outside the common hole. A dime covered the other nine pellet holes. I’ll take that any day from a springer and non-optical sights.
Nine of ten pellets can be covered by a dime. Not bad accuracy for open sights from a recoiling air rifle at 10 meters! The nine pellets measure 0.552 inches between centers. Shot ten enlarges that to 0.762 inches.
The next pellet I tested was the 8.4-grain JSB Exact dome that often does well in spring rifles. Once again, I got nine pellets in one hole and a single pellet outside. This time the group was tighter, as you can see in the photo, making this pellet one that the rifle really likes. The firing behavior was about the same as with the Crosman Premier lites.
Another tight group with a single stray. Notice that this group is definitely smaller than the one shot with Premier lites. The nine measure 0.418 inches between centers, and shot ten enlarges that to 0.876 inches.
The last pellet I tested was the RWS Hobby that had been used for sight-in. The rifle vibrated the most when this pellet was used, and of course the pellets went even higher than the first two I tested. We know from the velocity test that this particular pellet averages in the 860s, which is at the ragged top edge of power for this model, so perhaps Hobbys are a little too light for the gun.
Once more, there are nine pellets together and one off to the side. This group is noticeably larger than the other two, at 0.785 inches between centers for nine of them, while shot ten makes it 0.892 inches.
Please don’t try to make anything special out of the stray shot in each group. The only thing that can be said for sure is that all groups tended to spread horizontally, and the lone shot was always off to one side of the central group.
The bottom line
I’m pleased with the overall performance of this rifle. It’s performed admirably for a vintage springer, and I’m glad that it has the full U.S. power, given the effort it takes to cock the action. The one disappointment is that the Williams peep sight doesn’t adjust low enough to use at normal airgun distances. I hate to mount a scope on a vintage rifle like this, but I suppose I have to if I want to hit what I’m aiming at. These three groups give me confidence that I would be able to hit almost anything that comes within range.
Generally, I like the S70 rifle a lot better than the S55 N because of the length but also because of the fine condition of this particular gun.